#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "md5.h"





static unsigned char PADDING[64] =
{
	0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};

#define S11 7
#define S12 12
#define S13 17
#define S14 22
#define S21 5
#define S22 9
#define S23 14
#define S24 20
#define S31 4
#define S32 11
#define S33 16
#define S34 23
#define S41 6
#define S42 10
#define S43 15
#define S44 21

char* PrintMD5(uchar md5Digest[16])
{
	char chBuffer[256] = { 0 };
	char chEach[10] = { 0 };
	char *szRetBuffer = NULL;
	int nCount;
	int nRetLen = 0;
	
	for (nCount = 0; nCount < 16; nCount++)
	{
		sprintf(chEach, "%02X", md5Digest[nCount]);
		strncat(chBuffer, chEach, sizeof(chEach));
	}
	
	nRetLen = strlen(chBuffer);
	szRetBuffer = (char *)malloc(nRetLen + 4);
	strcpy(szRetBuffer, chBuffer);
	return szRetBuffer;
}

char* MD5String(char* szString)
{
	int nLen = strlen(szString);
	md5 alg;
	Init(&alg);
	Update(&alg, (unsigned char*)szString, (unsigned int)nLen);
	Finalize(&alg);

	return PrintMD5(Digest(&alg));
}


#define BUFFER_SIZE		4 * 1024
char* MD5File(const char* szFilename)
{
	char * res = NULL;
	FILE *pf = fopen(szFilename, "rb");
	if (pf) {
		uchar * buf = (uchar *)malloc(BUFFER_SIZE + 4);
		if (buf) {
			int n = 0;
			md5 alg;
			memset(buf, 0, BUFFER_SIZE + 4);
			Init(&alg);
			while ((n = fread(buf, 1, BUFFER_SIZE, pf)) > 0) {
				Update(&alg, buf, n);
			}
			Finalize(&alg);
			res = PrintMD5(Digest(&alg));
			free(buf);
		}
		fclose(pf);
	}
	return res;
}



void Init(md5 * pMd5)
{
	memset(pMd5->m_Count, 0, 2 * sizeof(uint4));

	pMd5->m_State[0] = 0x67452301;
	pMd5->m_State[1] = 0xefcdab89;
	pMd5->m_State[2] = 0x98badcfe;
	pMd5->m_State[3] = 0x10325476;
}

void Update(md5 *pMd5, uchar* chInput, uint4 nInputLen)
{
	uint4 i, index, partLen;

	// Compute number of bytes mod 64
	index = (unsigned int)((pMd5->m_Count[0] >> 3) & 0x3F);

	// Update number of bits
	if ((pMd5->m_Count[0] += (nInputLen << 3)) < (nInputLen << 3))
		pMd5->m_Count[1]++;

	pMd5->m_Count[1] += (nInputLen >> 29);

	partLen = 64 - index;

	// Transform as many times as possible.
	if (nInputLen >= partLen)
	{ 
		memcpy( &(pMd5->m_Buffer[index]), chInput, partLen );
		Transform(pMd5, pMd5->m_Buffer);

		for (i = partLen; i + 63 < nInputLen; i += 64) {
			Transform(pMd5, &chInput[i]);
		}

		index = 0;
	}
	else {
		i = 0;
	}

	// Buffer remaining input
	memcpy( &(pMd5->m_Buffer[index]), &chInput[i], nInputLen-i );
}

void Finalize(md5 *pMd5)
{
	uchar bits[8];
	uint4 index, padLen;

	// Save number of bits
	Encode (bits, pMd5->m_Count, 8);

	// Pad out to 56 mod 64
	index = (unsigned int)((pMd5->m_Count[0] >> 3) & 0x3f);
	padLen = (index < 56) ? (56 - index) : (120 - index);
	Update(pMd5, PADDING, padLen);

	// Append length (before padding)
	Update (pMd5, bits, 8);

	// Store state in digest
	Encode (pMd5->m_Digest, pMd5->m_State, 16);

	memset(pMd5->m_Count, 0, 2 * sizeof(uint4));
	memset(pMd5->m_State, 0, 4 * sizeof(uint4));
	memset(pMd5->m_Buffer,0, 64 * sizeof(uchar));
}


void Transform (md5 *pMd5, uchar* block)
{
	uint4 a = pMd5->m_State[0], b = pMd5->m_State[1], c =pMd5->m_State[2], d = pMd5->m_State[3], x[16];

	Decode (x, block, 64);

	// Round 1
	FF (&a, b, c, d, x[ 0], S11, 0xd76aa478);
	FF (&d, a, b, c, x[ 1], S12, 0xe8c7b756);
	FF (&c, d, a, b, x[ 2], S13, 0x242070db);
	FF (&b, c, d, a, x[ 3], S14, 0xc1bdceee);
	FF (&a, b, c, d, x[ 4], S11, 0xf57c0faf);
	FF (&d, a, b, c, x[ 5], S12, 0x4787c62a);
	FF (&c, d, a, b, x[ 6], S13, 0xa8304613);
	FF (&b, c, d, a, x[ 7], S14, 0xfd469501);
	FF (&a, b, c, d, x[ 8], S11, 0x698098d8);
	FF (&d, a, b, c, x[ 9], S12, 0x8b44f7af);
	FF (&c, d, a, b, x[10], S13, 0xffff5bb1);
	FF (&b, c, d, a, x[11], S14, 0x895cd7be);
	FF (&a, b, c, d, x[12], S11, 0x6b901122);
	FF (&d, a, b, c, x[13], S12, 0xfd987193);
	FF (&c, d, a, b, x[14], S13, 0xa679438e);
	FF (&b, c, d, a, x[15], S14, 0x49b40821);

	// Round 2
	GG (&a, b, c, d, x[ 1], S21, 0xf61e2562);
	GG (&d, a, b, c, x[ 6], S22, 0xc040b340);
	GG (&c, d, a, b, x[11], S23, 0x265e5a51);
	GG (&b, c, d, a, x[ 0], S24, 0xe9b6c7aa);
	GG (&a, b, c, d, x[ 5], S21, 0xd62f105d);
	GG (&d, a, b, c, x[10], S22,  0x2441453);
	GG (&c, d, a, b, x[15], S23, 0xd8a1e681);
	GG (&b, c, d, a, x[ 4], S24, 0xe7d3fbc8);
	GG (&a, b, c, d, x[ 9], S21, 0x21e1cde6);
	GG (&d, a, b, c, x[14], S22, 0xc33707d6);
	GG (&c, d, a, b, x[ 3], S23, 0xf4d50d87);
	GG (&b, c, d, a, x[ 8], S24, 0x455a14ed);
	GG (&a, b, c, d, x[13], S21, 0xa9e3e905);
	GG (&d, a, b, c, x[ 2], S22, 0xfcefa3f8);
	GG (&c, d, a, b, x[ 7], S23, 0x676f02d9);
	GG (&b, c, d, a, x[12], S24, 0x8d2a4c8a);

	// Round 3
	HH (&a, b, c, d, x[ 5], S31, 0xfffa3942);
	HH (&d, a, b, c, x[ 8], S32, 0x8771f681);
	HH (&c, d, a, b, x[11], S33, 0x6d9d6122);
	HH (&b, c, d, a, x[14], S34, 0xfde5380c);
	HH (&a, b, c, d, x[ 1], S31, 0xa4beea44);
	HH (&d, a, b, c, x[ 4], S32, 0x4bdecfa9);
	HH (&c, d, a, b, x[ 7], S33, 0xf6bb4b60);
	HH (&b, c, d, a, x[10], S34, 0xbebfbc70);
	HH (&a, b, c, d, x[13], S31, 0x289b7ec6);
	HH (&d, a, b, c, x[ 0], S32, 0xeaa127fa);
	HH (&c, d, a, b, x[ 3], S33, 0xd4ef3085);
	HH (&b, c, d, a, x[ 6], S34,  0x4881d05);
	HH (&a, b, c, d, x[ 9], S31, 0xd9d4d039);
	HH (&d, a, b, c, x[12], S32, 0xe6db99e5);
	HH (&c, d, a, b, x[15], S33, 0x1fa27cf8);
	HH (&b, c, d, a, x[ 2], S34, 0xc4ac5665);

	// Round 4
	II (&a, b, c, d, x[ 0], S41, 0xf4292244);
	II (&d, a, b, c, x[ 7], S42, 0x432aff97);
	II (&c, d, a, b, x[14], S43, 0xab9423a7);
	II (&b, c, d, a, x[ 5], S44, 0xfc93a039);
	II (&a, b, c, d, x[12], S41, 0x655b59c3);
	II (&d, a, b, c, x[ 3], S42, 0x8f0ccc92);
	II (&c, d, a, b, x[10], S43, 0xffeff47d);
	II (&b, c, d, a, x[ 1], S44, 0x85845dd1);
	II (&a, b, c, d, x[ 8], S41, 0x6fa87e4f);
	II (&d, a, b, c, x[15], S42, 0xfe2ce6e0);
	II (&c, d, a, b, x[ 6], S43, 0xa3014314);
	II (&b, c, d, a, x[13], S44, 0x4e0811a1);
	II (&a, b, c, d, x[ 4], S41, 0xf7537e82);
	II (&d, a, b, c, x[11], S42, 0xbd3af235);
	II (&c, d, a, b, x[ 2], S43, 0x2ad7d2bb);
	II (&b, c, d, a, x[ 9], S44, 0xeb86d391);

	pMd5->m_State[0] += a;
	pMd5->m_State[1] += b;
	pMd5->m_State[2] += c;
	pMd5->m_State[3] += d;

	memset(x, 0, sizeof(x));
}

// md5::Encode
// Encodes input (uint4) into output (uchar). Assumes nLength is
// a multiple of 4.
void Encode(uchar* dest, uint4* src, uint4 nLength)
{
	uint4 i, j;

	for (i = 0, j = 0; j < nLength; i++, j += 4)
	{
		dest[j] = (uchar)(src[i] & 0xff);
		dest[j+1] = (uchar)((src[i] >> 8) & 0xff);
		dest[j+2] = (uchar)((src[i] >> 16) & 0xff);
		dest[j+3] = (uchar)((src[i] >> 24) & 0xff);
	}
}

// md5::Decode
// Decodes input (uchar) into output (uint4). Assumes nLength is
// a multiple of 4.
void Decode(uint4* dest, uchar* src, uint4 nLength)
{
	uint4 i, j;

	for (i = 0, j = 0; j < nLength; i++, j += 4)
	{
		dest[i] = ((uint4)src[j]) | (((uint4)src[j+1])<<8) |
			(((uint4)src[j+2])<<16) | (((uint4)src[j+3])<<24);
	}
}

uchar * Digest(md5 *pMd5)
{
	return pMd5->m_Digest; 
}

uint4	rotate_left(uint4 x, uint4 n)
{ 
	return ((x << n) | (x >> (32-n))); 
}

uint4	F(uint4 x, uint4 y, uint4 z)
{
	return ((x & y) | (~x & z));
}

uint4	G(uint4 x, uint4 y, uint4 z)
{ 
	return ((x & z) | (y & ~z)); 
 }

uint4	H(uint4 x, uint4 y, uint4 z)
{ 
	return (x ^ y ^ z); 
}

 uint4	I(uint4 x, uint4 y, uint4 z)
{ 
	return (y ^ (x | ~z));
}

void FF(uint4* a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac)
{ 
	*a += F(b, c, d) + x + ac; 
	*a = rotate_left(*a, s); 
	*a += b;
}

void GG(uint4* a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac)
{ 
	*a += G(b, c, d) + x + ac; 
	*a = rotate_left(*a, s);
	*a += b; 
}

void HH(uint4* a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac)
{
	*a += H(b, c, d) + x + ac; 
	*a = rotate_left(*a, s); 
	*a += b; 
}

void II(uint4* a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac)
{ 
	*a += I(b, c, d) + x + ac;
	*a = rotate_left(*a, s); 
	*a += b; 
}